Nancy Black, 50, of Monterey admitted in federal court in San Jose to using pieces of gray whale blubber to lure orca whales near her boat in 2004 and 2005.

In 2004, a pod of killer whales killed a gray whale in the Monterey Bay National Marine Sanctuary, and chunks of the gray whale's blubber began floating on the surface of the water.

Black and her crew hauled the blubber onboard the Black Dog research boat, tied a rope to it so they could hold the fat close to the vessel, and recorded underwater video of the whales eating, prosecutors said.

"The orcas ate the blubber off the rope," Black wrote in her plea agreement. "After the orcas consumed the blubber we had handled, we repeated the process with other pieces of floating blubber in succession."

Black conducted a similar exercise in 2005, according to court documents.

Feeding marine mammals in the wild is a federal crime that carries a penalty of up to one year in prison and a $100,000 fine, according to court documents. Black is set to be sentenced in August.